SEARCH · PubMed Health

Results for “Continuous Evolution”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,333 records · Page 74Linked to original sources

PubMed2005

The victorian ethos of evolution.

The Victorian Age was the culmination of changes in the political, social, scientific, theological and cultural spheres throughout Europe. Darwin's newly elaborated evolutionary idea was the pivot for social Darwinism, a theory based on the gradual movement of the species toward greater self-awareness and strength. Shaw described this process in his play Man and Superman. Freud also utilized the concept in his libido theory. Horney interpreted the process as a psychic response to the intense societal pressures to succeed. A linkage of interdependence and progression of these ideas emerges as the world continues to evolve.

Biological Evolution↗

PubMed1994

A good eye for arthropod evolution.

Insect and crustacean lineages diverged over 500 Myr ago, and there are continuing uncertainties about whether they evolved from a common arthropod ancestor or, alternatively, they evolved independently from annelid worms. Despite the diversity of their limbs and lifestyles, the nervous systems of insects and crustaceans share many common features both in development and in function. Cellular and molecular embryology techniques reveal good evidence for homologies in the developing segmental ganglia. In the visual system, this seemingly common programme of insect and crustacean CNS development culminates in common adult neural function. Comparisons of the cellular anatomy and physiology of animals as diverse as flies and crayfishes indicate that the neural circuits in the lamina of their optic lobe have been inherited largely unchanged from a common ancestor with good compound eyes.

Animals↗

PubMed1992

Random genetic drift and selection in a triallelic locus: a continuous diffusion model.

The Kolmogorov forward diffusion equation is used to examine the evolution of three alleles at one locus under viability selection and random genetic drift. Separation of variables and Chebyschev approximations are employed to solve this equation for long times. As an example, one artificial viability set is examined in detail; its general implications for the evolution at a triallelic locus are discussed.

Alleles↗

PubMedDate not supplied

Measurement of benzene in the workplace and its evolution process, Part I: Overview, history, and past methods.

Benzene and its measurement continues to be important in the field of industrial hygiene. This two-part article reviews the history of occupational and environmental sampling and analysis of benzene from the early 1900s to the present. Part I provides an overview and details of the methods used in the past; history of the American Conference of Governmental Industrial Hygienists' threshold limit values for benzene; and reviews portable, grab, and integrated sampling methods as well as the various analytical methods. It is important to review and understand the past in order to predict future trends.

Air Pollutants, Occupational↗

PubMed1989

The evolution of growth trajectories and other complex quantitative characters.

Growth trajectories differ from many other quantitative characters in that they are characterized by a continuous function rather than by a finite number of discrete measurements. We review here recently developed methods for predicting the evolution of growth trajectories under the influence of natural or artificial selection. Using our method, analysis of genetic data from mice shows that the patterns of genetic variation arising from developmental processes impose constraints on evolution of growth trajectories. These constraints can be quantified to reveal the families of growth trajectories that can be produced by selection and those families that cannot. The data suggest there may be relatively few evolutionary degrees of freedom for growth trajectories despite the presence of abundant additive genetic variation to alter size and (or) growth rate at every age. The description of these constraints may be useful to both biologists who would like to determine the evolutionary options available to natural populations and to breeders who would like to alter growth trajectories to economically improve domesticated species. Our methods and conclusions can be generalized to other kinds of "infinite-dimensional" or complex characters, including morphological shapes and norms of reaction.

Age Factors↗

PubMed1992

Characterization of an Electron Transport Pathway Associated with Glucose and Fructose Respiration in the Intact Chloroplasts of Chlamydomonas reinhardtii and Spinach.

The role of an electron transport pathway associated with aerobic carbohydrate degradation in isolated, intact chloroplasts was evaluated. This was accomplished by monitoring the evolution of (14)CO(2) from darkened spinach (Spinacia oleracea) and Chlamydomonas reinhardtii chloroplasts externally supplied with [(14)C]fructose and [(14)C]glucose, respectively, in the presence of nitrite, oxaloacetate, and conventional electron transport inhibitors. Addition of nitrite or oxaloacetate increased the release of (14)CO(2), but it was shown that O(2) continued to function as a terminal electron acceptor. (14)CO(2) evolution was inhibited up to 30 and 15% in Chlamydomonas and spinach, respectively, by 50 mum rotenone and by amytal, but at 500- to 1000-fold higher concentrations, indicating the involvement of a reduced nicotinamide adenine dinucleotide phosphate-plastoquinone oxidoreductase. (14)CO(2) release from the spinach chloroplast was inhibited 80% by 25 mum 2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone. (14)CO(2) release was sensitive to propylgallate, exhibiting approximately 50% inhibition in Chlamydomonas and in spinach chloroplasts of 100 and 250 mum concentrations, respectively. These concentrations were 20- to 50-fold lower than the concentrations of salicylhydroxamic acid (SHAM) required to produce an equivalent sensitivity. Antimycin A (100 mum) inhibited approximately 80 to 90% of (14)CO(2) release from both types of chloroplast. At 75 mum, sodium azide inhibited (14)CO(2) evolution about 50% in Chlamydomonas and 30% in spinach. Sodium azide (100 mm) combined with antimycin A (100 mum) inhibited (14)CO(2) evolution more than 90%. (14)CO(2) release was unaffected by uncouplers. These results are interpreted as evidence for a respiratory electron transport pathway functioning in the darkened, isolated chloroplast. Chloroplast respiration defined as (14)CO(2) release from externally supplied [1-(14)C]glucose can account for at least 10% of the total respiratory capacity (endogenous release of CO(2)) of the Chlamydomonas reinhardtii cell.

Journal Article↗

PubMed2001

[Evolution and treatment response in microscopic colitis].

AIM: To study the clinical characteristics, treatment response and evolution in patients with microscopic colitis. MATERIAL AND METHODS: We performed a retrospective analysis of 24 patients (15 with collagenous colitis and 9 with lymphocytic colitis). Clinical and diagnostic features, treatment response and evolution according to the presence of maintenance therapy were evaluated. RESULTS: The mean age of the patients was 59.7 years and most were male. Nine patients took non-steroidal anti-inflammatory drugs (NSAID). No significant association was found with other drugs. Four patients presented associated rheumatological disease. Most patients presented insidious-onset diarrhea without pathological products, which was frequently associated with other symptoms (abdominal pain, bloating, weight loss, asthenia, tenesmus, and incontinence). Seven patients showed a slight increase in globular sedimentation rate. Fat in stools and radiological investigations (transit and opaque enema) were normal in patients who underwent these tests. Endoscopy revealed non-specific alterations in 42% of the patients while results were normal in the remaining patients. One patient showed clinical improvement on withdrawal of NSAIDs and 4 patients improved spontaneously. Clinical response was achieved in 7 of 13 patients treated with antimotility drugs, in 8 of 9 patients treated with salicylates, in 3 treated with oral corticoids, in 1 treated with cholestyramine and in 1 treated with topical budesonide. Nineteen patients required no maintenance therapy, 4 were administered salicylates and 1 was administered cholestyramine. After a mean follow-up of 42 months, evolution was chronic and intermittent in 14 patients and chronic and continuous in 1; 9 patients presented a single episode. No significant differences were found between patients administered maintenance therapy and those who were not or between collagenous colitis and lymphocytic colitis in the parameters analyzed. CONCLUSIONS: Microscopic colitis constitutes a group of diseases characterized by chronic diarrhea, few systemic effects and minimal radiological and/or endoscopic alterations. Evolution is characterized by recurrent episodes, with good response to treatment with cholestyramine, salicylates or corticoids when required.

Adult↗

PubMedDate not supplied

Growth of tracheal sutures with absorbable sutures in primates.

Postoperative wound healing is studied after tracheal suturing in 5 primates operated on in two stages. First by double level hemisection comparing continuous and interrupted sutures with polydioxanone. In a second stage: comparison of continuous sutures after tracheal segmental resection. The tracheas were harvested sequentially to study the evolution of the sutured zone by measuring its diameter and by histopathologic examination. The reduction of the tracheal diameter observed was not statistically significant after hemisection using continuous (p = 0.7) or interrupted sutures (p = 0.6). But after tracheal resection the stenosis was significant with continuous sutures (p < 0.05). Histologic study revealed that polydioxanone is well tolerated and is absorbed within 26 weeks. The authors recommend the use of continuous sutures to repair simple wounds and of interrupted sutures after tracheal resection anastomosis.

Animals↗

PubMedDate not supplied

[The evaluation of enteral nutritional support in the critical patient].

UNLABELLED: A prospective study of 40 patients for a period of 9 months was conducted, in order to evaluate the tolerance, clinical evolution and nutritional parameters in critical patients on enteral nutrition. In all cases, nutrients were administered enterally, by nasogastric tube and the administration method selected was continuous perfusion in most cases. 78.5 +/- 17% of estimated Kcal. were administered. During the study, the following aspects were studied: fasting time, type of diet, time during which enteral nutrition (EN) was maintained and reason for suspension, degree of derivation using nasogastric tube (NGT), number of bowel movements per day, antibiotic therapy ad gastric protection drugs as well as drugs administered for supporting mechanical ventilation and the evolution of the patient. Evolutional controls of the nutritional state were also conducted. Tolerance was seen to be good, especially in patients on continuous perfusion. With regard to the evolution of nutritional parameters, we observed maintenance of proteic levels with a slight recovery of retinol-binding protein (RBP) and no statistically significant differences between patients who died and those with a favourable development. The level of oligoelements was maintained, although below normal levels. CONCLUSIONS: EN is the ideal selection for the nutritional support of critical patients with functionally usefull gastrointestinal tracts. A good digestive tolerance was observed, and proteic levels maintained were similar to the initial ones, although with this type of diet, we recommend an additional intake of iron.

Aged↗

PubMedDate not supplied

Value of serum IgG subclasses in the prognosis of asthma in children with immunotherapy treatment.

Immunotherapy is an empirical treatment with proven clinical efficacy. Different results have been found when comparing the levels of the subclasses for immunoglobulin G and the clinical development during immunotherapy. A follow up study was carried out for one year on the IgG subclasses in 21 asthmatic children of both sexes and ages ranging from 8 to 11 years. The children were sensitized to Dermatophagoides Pteronyssinus and had undergone immunotherapy treatment. The clinical and analytical evaluation were carried out before treatment was started and later every four months. In terms of clinical evolution, the children were separated into two groups. The levels of IgG1 show different evolution in terms of a good or not good clinical evolution with a p of 0.056. Levels of IgG2 showed no differences. IgG3 shows a disorderly distribution. A continuous increase in IgG4 levels was observed from the start of immunotherapy though no differences in terms of clinical evolution were recorded. With the results obtained, it can be concluded that the gradual increase of IgG4 together with an early rise in IgG1 levels are related to the clinical efficacy of immunotherapy.

Allergens↗

PubMed2025

Comprehensive identification and analysis of clusters of tandemly duplicated genes reveal their contributions to adaptive evolution of green plants.

Tandem gene duplication occurred more frequently compared with the episodic whole-genome duplication (WGD), providing a continuous supply of genetic material for evolutionary innovation and adaptation to changing environments. The rising roles of clusters of tandemly duplicated genes (CTDGs) in the evolution of phenotypic diversity have been unraveled in mammals. However, the content and biological roles of CTDGs remain largely unknown in plants. Here, we comprehensively identified CTDGs in 220 published plant genomes representing major lineages of green plants. The number of CTDGs showed great variation across taxa, ranging from 0 to 6028. The size of CTDGs varied from 2 to 47 genes, with small clusters containing two members predominating. Interestingly, significant expansion of CTDGs was found in early-diverging land plants and is closely associated with the evolution of key traits (e.g., ABA response, plant cuticle, UV-B resistance) required for plants to conquer terrestrial environments. Functional enrichment analysis revealed conserved and specialized functional profiles among different sizes of CTDGs in both Arabidopsis thaliana and the bryophyte Physcomitrium patens. Small CTDGs were enriched in fundamental stress responses, including protein modification, signal transduction, and responses to diverse stress stimuli, while large CTDGs were enriched in more sophisticated processes such as plant hormone biosynthesis and signaling, plant-microbe interactions, and reproductive processes. Expression pattern analyses of CTDGs under different stress conditions in A. thaliana and P. patens revealed that the highest number of CTDGs showed differential expression under drought stress, suggesting important roles of CTDGs in the evolution of desiccation tolerance in early land plants. The results of this study provide new additions to our knowledge about the abundance of CTDGs across green plants and reveal their important contributions to enable plants to overcome stressful environments on land.

Gene Duplication↗

PubMed1991

Involvement of wound and climacteric ethylene in ripening avocado discs.

Avocado (Persea americana Mill. cv Hass) discs (3 mm thick) ripened in approximately 72 hours when maintained in a flow of moist air and resembled ripe fruit in texture and taste. Ethylene evolution by discs of early and midseason fruit was characterized by two distinct components, viz. wound ethylene, peaking at approximately 18 hours, and climacteric ethylene, rising to a peak at approximately 72 hours. A commensurate respiratory stimulation accompanied each ethylene peak. Aminoethoxyvinyl glycine (AVG) given consecutively, at once and at 24 hours following disc preparation, prevented wound and climacteric respiration peaks, virtually all ethylene production, and ripening. When AVG was administered for the first 24 hours only, respiratory stimulation and softening (ripening) were retarded by at least a day. When AVG was added solely after the first 24 hours, ripening proceeded as in untreated discs, although climacteric ethylene and respiration were diminished. Propylene given together with AVG led to ripening under all circumstances. 2,5-Norbornadiene given continuously stimulated wound ethylene production, and it inhibited climacteric ethylene evolution, the augmentation of ethylene-forming enzyme activity normally associated with climacteric ethylene, and ripening. 2,5-Norbornadiene given at 24 hours fully inhibited ripening. When intact fruit were pulsed with ethylene for 24 hours before discs were prepared therefrom, the respiration rate, ethylene-forming enzyme activity buildup, and rate of ethylene production were all subsequently enhanced. The evidence suggests that ethylene is involved in all phases of disc ripening. In this view, wound ethylene in discs accelerates events that normally take place over an extended period throughout the lag phase in intact fruit, and climacteric ethylene serves the same ripening function in discs and intact fruit alike.

Journal Article↗

PubMed2006

HIV global surveillance: foundation for retroviral discovery and assay development.

The high level of HIV genetic diversity has important implications for screening, diagnostic testing and patient monitoring. Continued diversification and global redistribution of HIV groups, subtypes and recombinants make it imperative that serological and molecular assays be designed and evaluated to ensure reliable performance on all HIV infections. Recognizing the importance of this issue, we initiated a comprehensive program to monitor global diversification of HIV, search for newly emerging variants, assemble large-volume panels of genetically and geographically diverse strains, and develop strategies to determine the impact of HIV diversity on assays used for detecting and monitoring HIV infection. Efforts to identify and characterize rare and emerging HIV strains have lead to the identification of HIV-1 group O, group N, and dual infections of groups M and O. A panel of plasma specimens was established that includes specimens collected from 12 countries in Africa, Asia, Europe, and South America; the panel comprises infections due to HIV-1 group M subtypes A, B, C, D, F, and G, as well as CRF01, CRF02, and unique recombinant forms, group N, and group O. Serological and molecular characterization of this unique panel has provided vital sequence data to support assay development and an invaluable source of well-defined specimens to evaluate and compare assay performance. The ability to address the challenge posed by ongoing evolution of HIV and the emergence of new variants requires continued surveillance of global HIV strain diversity, a sound scientific foundation for assay development, and suitable panels to evaluate and validate assay performance.

Africa↗

PubMedDate not supplied

A graph-based genetic algorithm and its application to the multiobjective evolution of median molecules.

In this paper we propose a novel graph-based genetic algorithm for the evolution of novel molecular graphs from a predefined set of elements or molecular fragments with an external objective function. A brief overview of existing genetic algorithm approaches in molecular design is provided followed by a description of our approach. The paper continues to suggest a novel application of this program to the multiobjective evolution of median molecules that are structurally representative of a set of objective molecules. We conclude with a summary of our initial results along with a discussion of a variety of improvements and applications of our approach.

Algorithms↗

PubMed2004

Directed enzyme evolution guided by multidimensional analysis of substrate-activity space.

The directed evolution of protein function frequently involves identification of mutants with improved properties from a population of variants obtained by mutagenesis. The selection of clones to parent the subsequent generation is crucial to the continued creation of superior progeny. In the present study, multivariate analysis guided the evolution of human glutathione transferase (GST) T1-1 to 65-fold enhanced alkyltransferase activity. Six alternative substrates monitored the substrate-activity space that characterized a mutant library of enzymes, obtained by recombination of DNA and heterologous expression in Escherichia coli. A subset of mutants was identified by their proximity in the targeted region of six-dimensional factor space. DNA from these mutants was recombined to create a new generation of GST variants from which an improved enzyme was isolated. The multidimensional cluster analysis is applicable to quantitative properties in any population of molecules undergoing evolution and can guide the tailoring of proteins, nucleic acids and other chemical structures to novel and improved functions.

Alkyl and Aryl Transferases↗

PubMed2005

Intra-host evolutionary dynamics of hepatitis C virus E2 in treated patients.

Hepatitis C virus (HCV) displays high genetic diversity. Inter-host sequence variability may mainly reflect a neutral drift evolution. In contrast, intra-host evolution may be driven by an adaptive selection to host responses to infection. Here, HCV E2 intra-host evolution in two patients during the course and follow-up of successive treatments with IFN-alpha and IFN-alpha/ribavirin was investigated. Phylogenetic analyses suggested that adaptive pressures prompt a continuous selection of viral variants derived from the previous ones (intra-lineage evolution) and/or a swapping of viral lineages during the course of the infection (inter-lineage evolution). Selection would act not only on the phenotypic features of hypervariable region 1 (HVR1) but also on those of the flanking regions. The pressures operate mainly at the amino acid level, but they also appeared to act on nucleotide sequences. Moreover, HVR1 heterogeneity seemed to be strongly constrained. This work contributes to the knowledge of HCV intra-host evolution during chronicity.

Antiviral Agents↗

PubMedDate not supplied

Beginning, growth, and transition.

This is what has happened and is happening. For those offended along the way, I apologize--but try us now. Prehospital and Disaster Medicine no longer is an experiment to see if a Journal of this ilk can be a success. It is. The experiment is over. Prehospital and Disaster Medicine is here to stay. Clearly, it meets many of the needs of a broadly based audience, and could meet needs of those who still are not participating in this exciting and enriching endeavor. I am grateful for the support of each of you, for that of the sponsoring organizations, and to the advertisers and publisher. A new phase has begun. The state of the Journal is dynamic, and it will continue to improve. It only can better meet your needs if you participate with us in its evolution. As always, your input is requested. Our aim is to provide you with the very best, and only with your continued input and support can we continue to build the medical disciplines of prehospital and disaster medicine.

Emergency Medicine↗

PubMed1999

Serum concentrations and clearances of folic acid and pyridoxal-5-phosphate during venovenous continuous renal replacement therapy.

OBJECTIVE: To determine to what extent hydrosoluble vitamins are removed by continuous renal replacement therapy (CRRT); to evaluate clearances, removal rates, and evolution of serum concentrations of folic acid and pyridoxal-5'-phosphate (P-5'-P), the active moiety of vitamin B6 during CRRT. DESIGN: A prospective, non-interventional, descriptive study on vitamin losses induced by CRRT. SETTING: Medical and surgical intensive care units in a tertiary university-affiliated hospital. PATIENTS: A total of ten critically ill patients in oligoanuric acute renal failure (five treated by continuous venovenous hemofiltration and five by continuous venovenous hemodiafiltration) with a mean effluent rate of 1801 +/- 468 ml/h. Nutritional support was not modified and additional vitamin supplements were not provided during study periods. MEASUREMENTS AND RESULTS: Concentrations of folic acid and P-5'-P were determined daily during CRRT. Samples for folic acid, P-5'-P, urea, and creatinine were taken simultaneously from the blood at the dialyzer inlet and from the effluent, at CRRT initiation, and daily thereafter over an average of 3.4 +/- 1.2 days. Samples were processed by immunochemiluminescence for folic acid and by radioenzymatic assay for P-5'-P determinations with normal ranges above 6.8 nmol/l and from 11.5 to 179.3 nmol/l, respectively. Marked decreases in serum folic acid and P-5'-P concentrations were noticed over time with mean daily reductions of 12.6 and 13.7%. Serum folic acid concentrations decreased from 42.7 to 16.0 nmol/l and serum P-5'-P decreased from 14.4 to 5.0 nmol/l in the blood coming in to the dialyzer over the study period. Clearances and removal rates were determined from the effluent side. During CRRT, mean (+/- SEM) folic acid and P-5'-P clearances were 20.5 +/- 6.3 ml/min (n = 34) and 13.2 +/- 10.6 ml/min (n = 22), whereas mean urea clearance was 27.1 +/- 5.1 ml/min (n = 26). Folic acid and P-5'-P removal rates were 27.0 +/- 34.2 and 3.4 +/- 2.0 nmol/h, corresponding to mean daily losses of nearly 650 and 80 nmol/day respectively. CONCLUSION: Significant losses of folic acid and P-5'-P (and most likely of other hydrosoluble vitamins) occur during CRRT. Considering that stores of most hydrosoluble vitamins are relatively low in critically ill patients, supplementation should be provided to patients treated similarly.

Aged↗